Several police officers were treated for injuries after being hit by rocks and at least one person was arrested as protesters crashed through barriers around the Albuquerque Convention Center, the police department said on Twitter.

The developments were part of a night of clashes between anti-Trump demonstrators and authorities as Trump addressed a crowd estimated at up to 8,000. Trump dismissed the chaos, tweeting: “Great rally in New Mexico, amazing crowd!”

Later he tweeted a more stern review of the crowd outside the rally.

“The protesters in New Mexico were thugs who were flying the Mexican flag,” Trump said. “The rally inside was big and beautiful, but outside, criminals!”

The unrest was the latest in a long line of sometimes violent protests outside Trump events across the nation. Trump was in California on Wednesday and planned a major rally in Anaheim. Police Chief Raul Quezada issued a warning to protesters Wednesday that “there is no room for violence in Anaheim.”

Protesters in Albuquerque, some hurling objects, chanted “Walk of shame!” at Trump supporters along a sidewalk that leads to the Albuquerque Convention Center, the Albuquerque Journal reported.

“This is an unlawful assembly,” Albuquerque police spokesman Simon Drobik told protesters over a loud speaker amid the chaos. Dereck Scott of Alburquerque, who uses a wheelchair, told the Associated Press he was hit with a plastic bottle. Protesters also charged at police horse patrols.

Riot police block off the Albuquerque Convention Center to anti-Trump protests following a rally and speech by Republican presidential candidate Donald Trump on May 24, 2016. (Photo: Brennan Linsley, AP)

Protest banners included “Trump is fascist” and “We’ve heard enough.” Police re-established the barricades and stopped most of the protesters outside the convention center. Some protesters eluded security and made it into the event, and several were removed as they repeatedly tried to interrupt Trump.

“They’re Bernie Sanders supporters,” Trump said, adding “we’re going to get about 40%” of Sanders’ supporters votes in the November election.

The candidate ridiculed the protesters, suggesting one “Go home to mommy.” The violence outside continued after the rally ended.

Albuquerque attorney Doug Antoon told AP rocks were flying through the convention center windows as he was leaving. Glass was breaking and landing near his feet. “This was not a protest, this was a riot. These are hate groups,” he said of the demonstrators.

“Appears that most of the @realDonaldTrump protestors have left & remaining contingent is only looking to cause trouble & be destructive,” the police department tweeted.